Left ventricular relaxation is often abnormal in a variety of cardiovascular disorders, including coronary artery disease, cardiomyopathies, and hypertension. Aging also is associated with abnormal diastolic relaxation, even in the absence of cardiovascular disease. This may be due to changes in cellular calcium metabolism that occur with aging, causing increased intracellular calcium concentration which in turn affects relaxation. We hypothesized that verapamil, a drug which blocks cell membrane calcium channels and reduces intracellular calcium, might improve left ventricular filling as it does in patients with cardiovascular disease. We studied 26 healthy male and female normal volunteers, ages 20-71 years, with radionuclide angiography before and after 3-4 days of verapamil treatment. Left ventricular relaxation can be assessed by analysis of the time activity curves obtained by radionuclide angiography. We found that left ventricular relaxation and filling is impaired in older, compared to younger normal volunteers, and that verapamil improves diastolic filling in the older, but not the younger, subjects. However, exercise performance did not change with verapamil. This suggests that impaired diastolic filling in elderly healthy subjects may indeed be secondary to altered calcium metabolism.